Sudan’s army has suspended its participation in talks over a ceasefire on Wednesday accusing its rivals of failing to honour their commitments.
It said "the rebels have never implemented a single one of the provisions of a short-term ceasefire which required their withdrawal from hospitals and residential buildings," an unnamed Sudanese government official told AFP news agency.
The withdrawal raises fears of renewed fighting that has displaced tens and thousands of people and killed nearly 2,000, according to figures by UN agencies and the Armed Conflict Location and Event Data Project.
The army said the paramilitary Rapid Support Forces (RSF) had also "repeatedly violated the truce", the official added.
US and Saudi mediators said late Monday that the warring parties had agreed to extend by five days a humanitarian truce they had frequently violated over the previous week.
The mediators admitted the truce had been "imperfectly observed" but said the extension "will permit further humanitarian efforts".
"The army is ready to fight until victory," army chief Abdel Fattah al Burhan declared during a visit to troops in the capital.
The RSF, led by Burhan's deputy-turned-foe Mohamed Hamdan Daglo, said they will "exercise their right to defend themselves" and accused the army of violating the truce.
In Darfur, on Sudan's western border with Chad, continued fighting "blatantly disregards ceasefire commitments", said Toby Harward, of the UN refugee agency.
More than half of Sudan's population - 25 million people - are now in need of aid and protection, the UN says.